The present invention relates to a flow-control valve for controlling flow of a heating fluid that is utilized to heat an environment, a thermostat located in the environment controlling current to a heat motor that, in turn, effects operation of the valve.
Flow-control valves for use in controlling fluid in the heating of an enclosed area or a machine or the like are quite common in the art and have normally included some form of a thermostat located in the environment to be heated that causes the valve to be opened or closed in accordance with a predetermined temperature of the environment. Prior to the instant invention, such flow-control valves have sometimes included electrically operated units having a solenoid operated device incorporated therein; and, although such a device served the purpose of opening or closing the valve as required, these devices were not always satisfactory for use in temperature control situation. Heat motors have also been incorporated in flow control devices and have been particularly useful in producing the required operation of a valve member because of the special characteristics of operation of a heat motor. However, the prior known devices that included heat motors did not provide for effective protection of the heat motor during the operation thereof; and, oftentimes, the heat motor would be burned out due to failure of the unit. It is also important in some instances to enable the control valve to be placed in a normally open position if for any reason the control device malfunctions and must be replaced. In the prior known devices, failure or malfunction of the heat motor or related control accessories resulted in a closing of the valve, which was not desirable if the valve unit had to be cleaned or otherwise serviced upon removal of the heat motor or control unit from the assembly.
Further, the prior known heat motor was somewhat ineffecient in the operation thereof since the heating elements associated therewith were assembled in layers and did not contribute altogether to an effective heating of the temperature responsive material within the motor. Under these conditions, unnecessary current was consumed that increased the cost of operation of the device. In most of the prior known heating units as employed for the control of fluid passing through a valve unit, the heat motor was responsive to the temperature of a thermostatic switch and protection of the heat motor was only accomplished through an end switch as associated therewith. Such end switches did not effectively protect the heating element because of the mechanical movement involved; and, quite frequently, the efficiency of the heat motor was materially reduced after only a short period of use.
The present invention is designed to overcome the above stated objections to the prior art devices, as will be hereinafter set forth.